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171.
172.
热拌超薄磨耗层是公路预防性养护的有效技术之一,基于某高速超薄磨耗层预防性养护工程,对不同级配进行路用性能试验研究。结果表明,不同级配混合料孔隙率随着2.36 mm筛孔通过率的增加而降低,细集料和矿粉均会填充混合料孔隙而且矿粉的填充效果为细集料的3倍。随着超薄磨耗层级配由粗变密,混合料马歇尔稳定度增加,肯塔堡飞散损失降低,疲劳寿命下降,采用矿粉作为填料的混合料性能显著优于细集料。相关性分析结果表明,超薄磨耗层混合料马歇尔稳定度,飞散损失以及疲劳性能与孔隙率存在较好的相关性,TSR结果与沥青膜厚度存在较好的相关性。超薄磨耗层的设计需要充分考虑孔隙率与沥青膜厚度指标。 相似文献
173.
三峡库区船舶碰撞能量损失方法的研究 总被引:1,自引:0,他引:1
采用外部碰撞力学方法计算2艘2 000 t级化学品船以不同速度,不同碰撞角,在不同碰撞点相撞后的能量损失,并利用显示动力有限元软件LS_DYNA模拟2艘化学品船在能量损失最大情况下碰撞的响应. 相似文献
174.
热油泵机械密封泄漏原因及对策 总被引:1,自引:0,他引:1
冷却系统结垢后,摩擦副端面温度过高,这是导致热油泵机械密封失败的根本原因.采取软化水夹套冷却和新增静环背冷等措施,可降低摩擦副端面温度,从而解决密封泄漏的问题. 相似文献
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176.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(10):1495-1514
Dither generated by rolling contact of wheel and rail smoothes dry friction damping provided by the primary suspension dampers of freight wagons and it should be taken into account in numerical simulations. But numerically the problem is non-smooth and this leads to long execution time during simulation, especially when the vehicle with friction dampers is modelled in the environment of an multi-body system simulation program, whose solver has to cope with many strong non-linearities. The other difficulty is the necessity of handling within the code a number of big volume files of recorded dither sampled with high frequency. To avoid these difficulties, a substitute model of two-dimensional dry friction exposed to dither is proposed that does not need application of dither during simulation, but it behaves as if dither were applied. Due to this property of the model, the excitation of the vehicle model by track irregularities may be supplied as low-frequency input, which allows fast execution and, the necessity of handling high-volume files of recorded dither is avoided. The substitute model is numerically effective. To identify parameters of the substitute model, a pre-processing employing a sample of the realistic dither is carried-out on a simple two-degrees-of-freedom system. The substitute model is anisotropic, describing anisotropic properties of the two-dimensional friction arising in the presence of one-dimensional dither. The model may be applied in other branches of engineering, for example, in mechatronics and robotics, where application of dither may improve the accuracy of positioning devices. 相似文献
177.
摩擦焊技术以其可靠的工艺、稳定的质量、安全的使用性在汽车零部件制造中得到认可。摩擦焊过程参数控制和工艺验证,是保证挂车车轴焊接可靠性的重要条件,对挂车车轴生产质量的稳定起着关键性作用。 相似文献
178.
Based on a shield-driven running tunnel project of Hangzhou Metro Line 2, this paper carries out field measuring of the ground surface deformation caused by two different shield machines in double-tube tunnelling in soft soil areas, obtains the laws of the surface deformation caused by shield-driven double-tube tunnelling and verifies the applicability of the modified Peck formula to double-tube tunnelling. The results show that in soft soil areas the impacts on ground surface deformation caused by different shield construction parameters in the previously and subsequently excavated tunnels are different, while the surface deformation changes sharply before and after the shield machine passing through the cutting face, and a rebound phenomenon occurs when the shield tail passes through the cutting face due to the influence of the grouting; The cutterhead torque of the shield machine in soft soil areas can be composed of five calculation factors, and the calculation results are in good agreement with the measured values. The larger the opening rate of the shield cutterhead is, the larger the average torque value will be, the higher the percentage of large ground loss rate will be, and the larger the maximum ground surface settlement will be; The ratio of cutterhead torque T to mucking volume per ring Q is used as the control parameter for analyzing the ground surface settlement, and a certain positive correlation between the ratio and the surface settlement value is determined, the smaller the cutterhead opening rate is, the more accurate the fitting results will be. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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180.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(4):501-526
Previous work in the railway technology laboratory at Virginia Polytechnic Institute and State University (Virginia Tech) focused on better capturing the dynamics of the friction wedge, modelled using three-dimensional rigid body dynamics with unilateral contact conditions. The current study extends the previous work to a half-bogie model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the sideframe. The half-bogie model was derived using MATLAB and functions as a three dimensional, dynamic, and multibody dynamics model comprised of four rigid bodies: a bolster, two friction wedges, and a sideframe assembly. This expanded model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and sideframe), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the sideframe are constrained to have only the vertical degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialised with a pre-defined yaw (rotation around the vertical axis) and the sideframe may be initialised with a pre-defined pitch/toe (rotation around the lateral axis). The results of the multibody dynamics in half-bogie model simulation are shown in comparison with results from NUCARS®, an industry standard in train-modelling software, for similar inputs. 相似文献